2007 ST3 won’t display neutral when in neutral. Switch has been removed and tested, it works. New switch was ordered JIC and tested and it works. There’s continuity from the switch cable connector to the ecu, but… the bloody light won’t indicate neutral when the switch is installed and connected. btw, there were no shim washers when I removed the original one so none have gone back in with the new switch. any suggestions anyone please ? photo for interest
The switch provides an earth connection to the ECU when the bike is in neutral (or perhaps it's the other way round with the ECU to earth except when in neutral). The ECU then signals to the dash via the Canbus to tell it to illuminate the warning light. Start by earthing the yellow/green wire that goes to the neutral switch and see if it has any effect on the neutral light. If no change the check the continuity of there yellow/green from the switch to the ECU. If that is ok then the fault possibly lies within the ECU or the dash. It can't be a Canbus fault or the dash wouldn't display, revs, speed nor coolant temperature.
It could even be the LEDs or their ballast resistors on the board within the dash itself. I found a couple of the Resistors for the LEDs had lifted one end on the PCB on my 1000SS: https://www.ducatiforum.co.uk/threads/instrument-repairs.80444/
The neutral light on the dash illuminates on ignition on as the dash runs through its check process. It also illuminates when the connector to the neutral switch is disconnected from the switch and grounded. This led me to believe the switch itself was faulty. Once removed (what a PITA that is ) and the switch was tested, by reconnecting the switch and grounding the end of the switch, the neutral light illuminated. It appears to me the switch isn’t making contact internally in the gear box when the bike is in neutral. The bike is in for a service and the owner did comment the neutral light had been playing up over the previous months ie not always illuminating when the bike was in neutral. I’m veering towards suspecting that somehow the neutral position cog within the gearbox isn’t fully aligning with the switch - if that’s even possible?
Does the switch plunger get pushed in or down it need to be fully out to make contact? If it needs to be fully out then maybe it needs a shim and under it. Usually there is a pip or a depression on the selector drum to operate the neutral switch and that can't get displaced.
Can't see how? if the gearbox is like that of a 2V/Desmoquattro (and I think it is) then there's a 'pip' on the shift drum that presses the switch - if it wasn't aligned then neither would the gears be. The switch can be positioned in/out using shims/washers so, unless there's a fault in your wiring I'd suspect the switch alignment.
To add, here's a pic of a shift drum I've got stashed away. The neutral indicator is the round headed rivety thing near the end (opposite to the racking mechanism) and this is what lifts the switch when in neutral, if it was out of sync then your gears would also be out. I suppose it's possible it's missing? but not sure if it could fall out in use - you should be able to see it through the switch hole and feel the switch lift when it's on it though so, if it's lifting but not enough to activate the switch then you'd need to move the switch further in by replacing the shim with a thinner one or even removing it completely.
And that the neutral indication problem appeared intermittent which doesn't appear consistent with the 'rivety thing' dropping out, I would think that if it fell out then the neutral indication would stop working immediately. Sa sounds like a wiggly amps problem. Can the OP advise if, with the new switch connected to the wiring harness and the switch body earthed, with ignition on, if pushing the switch plunger in and out results in the neutral light going on and off? And then with the switch installed, measure the resistance between the electrical connector on the switch and the bikes crankcase when going through the gears and back into neutral. The reading should be open circuit or continuity when in gear vs neutral. That should confirm if the problem is with the switch or the wiring.
The switch itself isn’t a plunger type ie the knob on the end doesn’t move in/out making/breaking contact within the switch. The ‘switch’ isn’t really a switch in the normal sense at all but is a rod of metal encased in an insulating material within the threaded body which screws into the crankcase. There’s no circuit until the round nipple on the gear shaft, see @Dukedesmo ’s photo above, comes into contact with the nipple on the end of the neutral switch which then completes the circuit to ground and the ecu recognises that circuit and illuminates the green N light in the dash and permits the engine to start. However, what the OP, ie me, can confirm is that he is, quite arguably a complete numpty . It transpires that all the while I was turning the crank, whilst doing the Desmo and belt service, the gear box was in a false neutral between gears 2 & 3 . Thus the crank would turn without the gear box/rear wheel turning and if I put it in what I thought was 1st, or 2nd (but really was 2nd or 3rd) to be able to move the rear wheel to rotate the cams (so I could stay on the same side of the bike as the cams) and then put it back into what I thought was neutral, it wasn’t the real neutral and there was no nipple to make contact with the ‘switch’. I discovered this because thinking it through earlier I thought, it’s just not possible, it’s got to be something simple, I’ll just check I really am in neutral I hold my hand up - what a muppet .
I wanted to come up with a sincere post praising you for your honesty, trying to reassure you that we all make mistakes, it could happen to anyone etc, but all I could manage is: . . . . . . . . .
Intrigued now... It the 'plunger' on the end of the switch doesn't move, is the detent ball in the gear shaft spring loaded then? Surely one or the other is. Furthermore, now that you have found correct neutral, does the neutral light work correctly. And last but not least, if the original indication was becoming intermittent what was the cause?
Maybe...Must be something magical to justify the price! Pretty sure the neutral switch on older bikes was a simple plunger switch (which would explain the contact makings on the selector drum photo in an earlier post). If it's a prox switch then doesn't look like the most sensible design as it's pretty difficult to measure the air gap (or gearbox with engine oil splashing around equivalent) when fitting a replacement without splitting the crankcases. Hopefully someone will be along who can explain how it works for the benefit of mankind....
I can’t speak for the nipple/ball on the gear box shaft but the neutral switch definitely isn’t a plunger. It’s definitely a fixed rod. Thankfully, yes I’m not sure. The rod breaking down with age? The tip getting worn away and thus not making good contact with the nipple on the gear shaft? I’m not sure. I did a simple resistance test on the two switches, the old read 15mOhm the new 6, who knows if that’s significant or not. ps. On this bike It’s a single wire from the socket that connects to the neutral switch which feeds directly from pin14 (iirc) of the ECu. A current is passed along it, from the ECU, which grounds and completes the circuit when the bike is in (THE CORRECT) neutral. For anyone else reading this FYI it’s a 14mm nut size on the switch and a spark plug socket fits perfectly. The spark plug socket I have has both a 3/4” drive hole and a 17mm hex on the end of it and it’s just possible, but fiddly, to get a 17mm ratchet spanner through the frame, onto the spark plug socket and then turn it. Once it’s cracked loose it can be undone with your fingers but it’s a fiddly 1/6th of a revolution at a time .
If it's a single wire (not multicore) then it's not some kind of proximity/sensor, sounds like a plunger switch to me. The older bikes (like mine) use a 2-wire switch and switch positive to the neutral light whereas later bikes are a 1 wire, simply switching earth (negative) from the engine casing to the light (like the oil pressure switch). Maybe the plunger part is seized or missing?
It is possible that the switch does have a plunger but has a really strong spring behind it to prevent false switching. Trying to depress it with your hand will not have the same force as the engine/gearbox nipple being forced against it. Try depressing it on a hard surface with pressure (make sure it is something metal and not the wooden dining room table!!). You could use a meter at the same time to check for continuity.
